A comparison of PegIntron/ribavirin versus Pegasys/ribavirin in the IDEAL
trial indicated that SVR rates were similar, but the likelihood of relapse
was significantly lower in the PegIntron arm. Some experts expressed
skepticism about these findings since the ribavirin regimens used were not
the same in both treatment arms (both were administered according to their
package insert dosing instructions at the time).

Following up on these findings, German researchers performed a retrospective
analysis to evaluate whether ribavirin dose might explain these findings.
Results were published in the April 2009 issue of Scandanavian Journal of
Gastroenterology.

As background, they noted that in the IDEAL trial, patients weighing > 105
kg reach a maximum ribavirin dose of 13.2 mg/kg ribavirin in the PegIntron
arm regimen compared with 11.3 mg/kg in the Pegasys arm.

The 84 patients with a ribavirin dose > 13.2 mg/kg (n=84) had a relapse rate
of 19.0%, in contrast to 71.4% for the 14 patients with a ribavirin dose <
13.2 mg/kg (P = 0.0013).

The SVR rate was significantly higher in the > 13.2 mg/kg ribavirin dose
group compared with the < 13.2 mg/kg group (59.5% vs 28.6%, respectively).

Based on these findings, the authors concluded, "Weight-adapted ribavirin
dosing in combination with [pegylated interferon alfa-2a] to avoid giving
low doses of ribavirin should be evaluated. This will minimize relapse,
especially in HCV genotype 1 patients."

Medical Department, Hepatology and Gastroenterology, Friedrich-Alexander
University of Erlangen, Germany.